The present invention relates to a static charge elimination method for eliminating static charges inside a wall structure of a resin vessel, a sterilization and filling method for a resin vessel for eliminating charges inside a wall structure of a resin vessel during a sterilization process of the resin vessel, a filling and capping method for a resin vessel, a static charge elimination apparatus for a resin vessel, and a sterilization and filling system for a resin vessel.
In a conventional technology, there has been widely known an electron beam sterilization apparatus for sterilizing a resin vessel such as a PET bottle by being irradiated with an electron beam. It has also conventionally known that the resin vessel becomes charged when being irradiated with the electron beam. In such a case, dust and dirt are attracted to the charged resin vessel, which may cause an undesirable matter. Then, there have been provided several apparatus for eliminating static charge from a charged resin vessel (for example, refer to Japanese Patent Application Laid-open Publication Nos. 2006-216453 and 2009-51517: Patent Documents 1 and 2).
The above Patent Document 1 discloses an invention concerning a static charge elimination apparatus. This static charge elimination apparatus is provided with a hollow ionizing chamber, in which a flow-in port through which air or unreactive gas is introduced is formed at an upper central portion in this ionizing chamber, and a flow-out port is also formed at a lower central portion thereof in a fashion opposed to the flow-in port.
Moreover, on the side portion of the ionizing chamber, a soft X-ray generating portion of a soft X-ray generator is positioned, and a soft X-ray generated through the soft X-ray generating portion is radiated into the ionizing chamber through a soft X-ray irradiating window formed in the side surface portion of the ionizing chamber. The soft X-ray radiated into the ionizing chamber acts to ionize the air or unreactive gas to thereby generate positive or negative ions.
Furthermore, a back electrode (i.e., back plate) is disposed on an inner surface of the ionizing chamber, and a filter electrode, having a perforated plate shape, is also disposed at a front (tip) end portion of the flow-out port. In addition, a plate-shaped induction electrode is mounted to the lower portion of the ionizing chamber on the same level as the back plate and the filter electrode. Power sources for generating alternating current are connected to the back electrode, the filter electrode and the induction electrode so that the polarities of the voltages applied to these electrodes are switched alternately.
The static elimination apparatus disclosed in the above Patent Document 1 is disposed above a resin film, which is an object from which static charge is eliminated, air or unreactive gas is introduced into the ionizing chamber through the flow-in port, and the soft X-ray is emitted through the soft X-ray irradiating window, thus generating positive and negative ions in the ionizing chamber.
Then, the back electrode, the filter electrode and the induction electrode are applied with the voltage having the same polarity by the alternating current sources, whereby, in the ionizing chamber, ions having the same polarity as that of the applied voltage (unipolar ions) are generated, and on the other hand, by the filter electrode and the induction electrode disposed in opposition to the resin film, on the surface of the resin film, a charge having a polarity reverse to that of the applied voltage is induced.
As mentioned above, the charge induced on the surface of the resin film and charge originally existing thereon are neutralized by blowing the unipolar ions generated in the ionizing chamber. The charge induced on the surface of the resin film and the polarities of the unipolar ions generated in the ionizing chamber are alternately switched in positive or negative state by alternately switching, in positive or negative state, the polarities of the voltages to be applied by the alternating current power source, and as a result of the repetition of these operations, the charges inside the resin film can be surely eliminated.
Furthermore, the Patent Document 2 discloses a method of manufacturing a vessel with an inner content capable of suppressing the charging of a vessel body. In this manufacturing method, a lid is mounted to a neck portion near a mouth of the vessel body before sealing, and the vessel body is arranged in a conveyance holder in a state in which the lid is directed downward. A seal portion disposed on a side reverse to the vessel lid is opened, and an inner content filling nozzle is inserted into the vessel from the upper side of the opening before the sealing of the same and fills the vessel with the inner content such as liquid.
When a predetermined amount of the inner content fills the vessel, the filling is stopped and the filling nozzle is pulled upward outside the vessel body. Thereafter, a conducting member or material is inserted inside the vessel body so as to contact the inner content to thereby eliminate the static charge of the vessel body through the inner content and the conducting member or material.
Furthermore, in another conventional technology, there is also disclosed a method in which a filling nozzle and a conducting member are inserted into the vessel body from the upper side thereof before the sealing of the same, and the conducting member is contacted to the inner content while filling the inner content through the filling nozzle to thereby eliminate the static charges of the vessel body through the inner content and the conducting member.
It is however found that it is difficult to completely eliminate charges charged inside a resin vessel (in the interior of a resin material forming the vessel) by the structure in which the ions are blown on an object subjected to the static charge elimination disclosed in the above Patent Document 1 and by the structure in which a conducting member or material is inserted into an inner content to fill a resin vessel as in a method of manufacturing a resin vessel in which the inner content fills the resin vessel as disclosed in the above Patent Document 2, thus being inconvenient.